Thus, the invention relates to a baby carrier of a kind which includes a harness of the general type comprising chest straps and a carrier poach mounted on the harness, which carrier pouch is formed of a front piece provided with leg openings or a part thereof and adapted to be carried on the chest side of a wearer.
When carrying a child on the chest side, particularly when the child no longer is an infant and the child starts to “discover” the world around himself, it is desirable to be able to carry the child on one hand face-to-face and on the other hand in forward-facing position, i.e. the child having its face directed from wearer.
When changing the seat position of the child in the baby carrier from face-to-face to the forward-facing position, for instance, a great change is however needed of the geometry of the baby carrier in the region of the pelvis of the child, since the effective width of the seat support of the baby carrier should be able to be changed between a relatively wide seat support, when the child is carried face-to-face, and a relative narrow seat support, when the child is carried in a forward-facing position. With a narrow seat support the child may easily move the legs, which is important so that the motor function is developed in an advantage way. This change of the width of the seat support should be able to be made in a fast and simple way with the baby carrier carried by the wearer, preferably even when the child is sitting in the baby carrier.
More preferably it is desirable that the seat position of the child in the baby carrier should be able to be changed in such a way that the child can be seating:                i) face-to-face with its legs placed around the waist of the wearer of the baby carrier, whereby a wide seat support is needed,        ii) face-to-face with total free movement of the legs of the child, whereby a relatively narrow seat support is needed, and        iii) in forward-facing position with total free movement of the legs of the child, whereby also in this case a relatively narrow seat support is needed. Thus, it is the position of the legs of the child which should be changed when changing the seat position of the child.        
A further reason why the width of the seat support must be changed is that, when the child is sitting in forward-facing position, the seat support must not have such a width that it will force apart, part, the legs of the child, i.e. it is desirable to have a seat posture which is as ergonomically as possible for the child with correct position of the legs. If however the legs are forced apart of the seat support a pressure may arise on the inside of the legs of the child at the area of the thighs and against possible blood vessels in said area which may lead to reduced blood circulation in the legs. It is particularly important that the seat support is not too wide when carrying a heavier child.
U.S. Pat. No. 6,443,339 B1 describes a baby carrier used for holding a child in both face-to-face and in forward-facing position and provided with a width-reducing member for reducing the width of a lower portion of the backrest when the child is held in the forward-facing position. The width reducing member is described and shown to include a string adapted to cooperate with loops, a belt the length of which may be adjusted or D-rings adapted to cooperate with hooks so as to reduce the width of the lower portion. However, the width of the lower portion of the backrest cannot be adjusted to such an extent which is desirable.